Israel has signed a contract to purchase $125 million worth of coal from Colombia during the next five years, the Energy Ministry announced Tuesday.

Australia and South Africa are currently Israel’s principal suppliers of coal. But Colombia will supply 600,000 tons next year, about 15 percent of Israel’s requirements, and the contract allows the amount to be increased to 1 million tons, the ministry said.

Israel needs additional supplies of coal. About half of its electrical capacity is produced by the coal-fired Hadera power station.

The first of two new coal-fired generating plants will go into service at the port of Ashkelon at the end of 1990. The second unit is scheduled to start operating in 1991.

Meanwhile, investigators from the U.S. Congress were in Israel this week to question an Israel Defense Force reserve officer about allegations that he trained assassination squads for Colombia’s drug cartel.

Officials of the Senate subcommittee on investigations have questioned Lt. Col. Yair Klein, who heads a company called Hod HaHanit (Spear-head), which specializes in security, as well as several of Klein’s employees.

Klein had a contract last year to provide military training and equipment to private clients in Colombia. He insists he trained security guards for ranchers and farmers who were plagued by cattle rustlers and guerrillas.

But a videotape televised in August by NBC News showed Klein personally instructing a group alleged to be mercenaries in the employ of Colombian drug barons.

A Foreign Ministry spokesman said Israel is cooperating with the American inquiry to help combat the drug traffic and to prevent the future involvement of Israeli nationals in dubious enterprises in Colombia.

Klein was questioned by the IDF last summer. In the fall, he reportedly had been willing to come to Washington to be grilled on his Colombian connections. He said at the time that he would do so, despite an international warrant for his arrest that Colombia requested from Interpol.

A number of retired IDF officers and reservists are licensed by the Defense Ministry to engage in private arms dealing abroad or to provide security systems and training for legal clients overseas.